While I was doing preflight walkaround the first officer obtained, wrote down and readback the following clearance for our flight. Cleared to tus via loop 5 departure daggett transition, needles direct salt river dingo 4 arrival, tus. Approaching needles VOR, to refresh my memory, I asked the first officer how we were routed after needles VOR. He referred to the copy of the clearance and stated that we were cleared needles direct salt river. Passing needles I turned direct to salt river and continued along this route for approximately 30 mi. At this point, lax center called and asked what route we were following. When told that we were direct to salt river we were asked to turn left to 030 degree heading and descended to FL290. Since this was a major course/altitude change, I asked the center if there was a problem. I was told that we had been on a converging course with another aircraft but that all sep standards had been met and no conflict had occurred. The lax center controller advised us that his strip on our flight showed that we had been originally cleared to tus, needles-drake-salt river and not needles direct salt river. It appears very possible that very similar sounding words (drake/direct) may have caused this potential conflict problem enroute to tus. The first officer doesn't remember hearing the word drake being used. He was very positive about the course. Looking at the high altitude commercialenrte chart, this seemed to be a logical course to take to tus (the clearance issued in lax was a reroute of our pre-filed course which was: orange departure-trm-blh-J50-gbn-dingo 4). And, salt river VOR was a gateway to tus on the dingo STAR commercial plate (drake VOR isn't even shown on this plate. There just wasn't any clue available to the crw to indicate that needles direct to salt river was possibly an incorrect course. One possible solution would be to have clearance delivery use 'drake VOR' instead of just 'drake' to avoid any confusion with a 'direct' course. Drake VOR may have to be renamed to avoid crews/pilots from confusing a routing over drake VOR as a direct routing to another VOR. Supplemental information from acn 81888: when clearance delivery was called they advised us that it would be a rull route readout. The new clearance was a loop departure (ie, north routing). I copied the clearance just as I heard it and read back completed just what I had copied. The problem was that the original clearance from clearance delivery was loop 5 departure, daggett transition, needles, drake, salt river, dingo arrival tucson. I heard and read back needles direct, salt river (not drake).

Narrative: WHILE I WAS DOING PREFLT WALKAROUND THE F/O OBTAINED, WROTE DOWN AND READBACK THE FOLLOWING CLRNC FOR OUR FLT. CLRED TO TUS VIA LOOP 5 DEP DAGGETT TRANSITION, NEEDLES DIRECT SALT RIVER DINGO 4 ARR, TUS. APCHING NEEDLES VOR, TO REFRESH MY MEMORY, I ASKED THE F/O HOW WE WERE ROUTED AFTER NEEDLES VOR. HE REFERRED TO THE COPY OF THE CLRNC AND STATED THAT WE WERE CLRED NEEDLES DIRECT SALT RIVER. PASSING NEEDLES I TURNED DIRECT TO SALT RIVER AND CONTINUED ALONG THIS ROUTE FOR APPROX 30 MI. AT THIS POINT, LAX CENTER CALLED AND ASKED WHAT ROUTE WE WERE FOLLOWING. WHEN TOLD THAT WE WERE DIRECT TO SALT RIVER WE WERE ASKED TO TURN LEFT TO 030 DEG HDG AND DESCENDED TO FL290. SINCE THIS WAS A MAJOR COURSE/ALT CHANGE, I ASKED THE CENTER IF THERE WAS A PROB. I WAS TOLD THAT WE HAD BEEN ON A CONVERGING COURSE WITH ANOTHER ACFT BUT THAT ALL SEP STANDARDS HAD BEEN MET AND NO CONFLICT HAD OCCURRED. THE LAX CENTER CTLR ADVISED US THAT HIS STRIP ON OUR FLT SHOWED THAT WE HAD BEEN ORIGINALLY CLRED TO TUS, NEEDLES-DRAKE-SALT RIVER AND NOT NEEDLES DIRECT SALT RIVER. IT APPEARS VERY POSSIBLE THAT VERY SIMILAR SOUNDING WORDS (DRAKE/DIRECT) MAY HAVE CAUSED THIS POTENTIAL CONFLICT PROB ENROUTE TO TUS. THE F/O DOESN'T REMEMBER HEARING THE WORD DRAKE BEING USED. HE WAS VERY POSITIVE ABOUT THE COURSE. LOOKING AT THE HIGH ALT COMMERCIALENRTE CHART, THIS SEEMED TO BE A LOGICAL COURSE TO TAKE TO TUS (THE CLRNC ISSUED IN LAX WAS A REROUTE OF OUR PRE-FILED COURSE WHICH WAS: ORANGE DEP-TRM-BLH-J50-GBN-DINGO 4). AND, SALT RIVER VOR WAS A GATEWAY TO TUS ON THE DINGO STAR COMMERCIAL PLATE (DRAKE VOR ISN'T EVEN SHOWN ON THIS PLATE. THERE JUST WASN'T ANY CLUE AVAILABLE TO THE CRW TO INDICATE THAT NEEDLES DIRECT TO SALT RIVER WAS POSSIBLY AN INCORRECT COURSE. ONE POSSIBLE SOLUTION WOULD BE TO HAVE CLRNC DELIVERY USE 'DRAKE VOR' INSTEAD OF JUST 'DRAKE' TO AVOID ANY CONFUSION WITH A 'DIRECT' COURSE. DRAKE VOR MAY HAVE TO BE RENAMED TO AVOID CREWS/PLTS FROM CONFUSING A ROUTING OVER DRAKE VOR AS A DIRECT ROUTING TO ANOTHER VOR. SUPPLEMENTAL INFO FROM ACN 81888: WHEN CLRNC DELIVERY WAS CALLED THEY ADVISED US THAT IT WOULD BE A RULL ROUTE READOUT. THE NEW CLRNC WAS A LOOP DEP (IE, N ROUTING). I COPIED THE CLRNC JUST AS I HEARD IT AND READ BACK COMPLETED JUST WHAT I HAD COPIED. THE PROB WAS THAT THE ORIGINAL CLRNC FROM CLRNC DELIVERY WAS LOOP 5 DEP, DAGGETT TRANSITION, NEEDLES, DRAKE, SALT RIVER, DINGO ARR TUCSON. I HEARD AND READ BACK NEEDLES DIRECT, SALT RIVER (NOT DRAKE).

Data retrieved from NASA's ASRS site as of August 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.